Abstract/Description

Planting rice further apart reduces the risk of attacks by the rice gall midge which is a serious pest in Asia and many African countries. The larvae feed on the young rice shoots which then develop the characteristic hollow leaf galls, called...

Notes

Planting rice further apart reduces the risk of attacks by the rice gall midge which is a serious pest in Asia and many African countries. The larvae feed on the young rice shoots which then develop the characteristic hollow leaf galls, called onion leaf tubes or silver shoots, which prevent panicle development and thus reduce yield.
Over the last two years, researchers at the National Cereals Research Institute in Nigeria have been conducting trials with varying planting distances and nitrogen levels. The yields from areas planted in rows 30 cm x 30 cm apart were about 10% higher than those planted at 10 cm x 10 cm due to the fact that there were more silver shoots and less mature panicles at the closer planting distance. It appears that the closer spacing provides a micro-climate more favourable to this pest and that the base of the plants receive less light. The percentage of silver shoots with closer spacing was about 55 % over two years compared to 45 % at a wider spacing.
In the first year, higher nitrogen applications increased pest damage but did not affect the gall midge infestation. In the second year, extra nitrogen seemed to increase both the number of insects and the extent of gall midge damage.
Source: Tropical Pest Manager, April-June, 1987
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